From: john stultz <johnstul@us.ibm.com>
Here are my fixes to Dominik's patch. It cleans up some of the math, adds
lost-tick compensation and monotonic_clock, fixes up a bit of the ACPI
table mapping, and moves the config option under the ACPI menu.
25-akpm/Documentation/kernel-parameters.txt | 2
25-akpm/arch/i386/Kconfig | 18 -----
25-akpm/arch/i386/kernel/acpi/boot.c | 10 ++-
25-akpm/arch/i386/kernel/timers/timer_pm.c | 93 ++++++++++++++++++++++------
25-akpm/drivers/acpi/Kconfig | 19 +++++
5 files changed, 103 insertions(+), 39 deletions(-)
diff -puN arch/i386/Kconfig~acpi-pm-timer-fixes arch/i386/Kconfig
--- 25/arch/i386/Kconfig~acpi-pm-timer-fixes Mon Nov 17 12:09:48 2003
+++ 25-akpm/arch/i386/Kconfig Mon Nov 17 12:09:48 2003
@@ -411,24 +411,6 @@ config HPET_TIMER
config HPET_EMULATE_RTC
def_bool HPET_TIMER && RTC=y
-config X86_PM_TIMER
- bool "Power Management Timer Support"
- depends on (!X86_VISWS && !X86_VISWS) && EXPERIMENTAL
- default n
- help
- The Power Management Timer is available on all ACPI-capable,
- in most cases even if ACPI is unusable or blacklisted.
-
- This timing source is not affected by powermanagement features
- like aggressive processor idling, throttling, frequency and/or
- voltage scaling, unlike the commonly used Time Stamp Counter
- (TSC) timing source.
-
- So, if you see messages like 'Losing too many ticks!' in the
- kernel logs, and/or you are using a this on a notebook which
- does not yet have an HPET (see above), you should say "Y"
- here. Otherwise, say "N".
-
config SMP
bool "Symmetric multi-processing support"
---help---
diff -puN arch/i386/kernel/acpi/boot.c~acpi-pm-timer-fixes arch/i386/kernel/acpi/boot.c
--- 25/arch/i386/kernel/acpi/boot.c~acpi-pm-timer-fixes Mon Nov 17 12:09:48 2003
+++ 25-akpm/arch/i386/kernel/acpi/boot.c Mon Nov 17 12:09:48 2003
@@ -327,15 +327,19 @@ static int __init acpi_parse_hpet(unsign
}
#endif
-/* detect the location of the ACPI PM Timer
+/* detect the location of the ACPI PM Timer */
#ifdef CONFIG_X86_PM_TIMER
extern u32 pmtmr_ioport;
static int __init acpi_parse_fadt(unsigned long phys, unsigned long size)
{
- struct fadt_descriptor_rev2 *fadt;
+ struct fadt_descriptor_rev2 *fadt =0;
- fadt = __va(phys);
+ fadt = (struct fadt_descriptor_rev2*) __acpi_map_table(phys,size);
+ if(!fadt) {
+ printk(KERN_WARNING PREFIX "Unable to map FADT\n");
+ return 0;
+ }
if (fadt->revision >= FADT2_REVISION_ID) {
/* FADT rev. 2 */
diff -puN arch/i386/kernel/timers/timer_pm.c~acpi-pm-timer-fixes arch/i386/kernel/timers/timer_pm.c
--- 25/arch/i386/kernel/timers/timer_pm.c~acpi-pm-timer-fixes Mon Nov 17 12:09:48 2003
+++ 25-akpm/arch/i386/kernel/timers/timer_pm.c Mon Nov 17 12:09:50 2003
@@ -30,7 +30,12 @@ u32 pmtmr_ioport = 0;
/* value of the Power timer at last timer interrupt */
static u32 offset_tick;
+static u32 offset_delay;
+static unsigned long long monotonic_base;
+static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED;
+
+#define ACPI_PM_MASK 0xFFFFFF /* limit it to 24 bits */
static int init_pmtmr(char* override)
{
@@ -62,24 +67,89 @@ static int init_pmtmr(char* override)
return -ENODEV;
}
+static inline u32 cyc2us(u32 cycles)
+{
+ /* The Power Management Timer ticks at 3.579545 ticks per microsecond.
+ * 1 / PM_TIMER_FREQUENCY == 0.27936511 =~ 286/1024 [error: 0.024%]
+ *
+ * Even with HZ = 100, delta is at maximum 35796 ticks, so it can
+ * easily be multiplied with 286 (=0x11E) without having to fear
+ * u32 overflows.
+ */
+ cycles *= 286;
+ return (cycles >> 10);
+}
/*
* this gets called during each timer interrupt
*/
static void mark_offset_pmtmr(void)
{
+ u32 lost, delta, last_offset;
+ static int first_run = 1;
+ last_offset = offset_tick;
+
+ write_seqlock(&monotonic_lock);
+
offset_tick = inl(pmtmr_ioport);
- offset_tick &= 0xFFFFFF; /* limit it to 24 bits */
+ offset_tick &= ACPI_PM_MASK; /* limit it to 24 bits */
+
+ /* calculate tick interval */
+ delta = (offset_tick - last_offset) & ACPI_PM_MASK;
+
+ /* convert to usecs */
+ delta = offset_delay + cyc2us(delta);
+
+ /* convert to ticks */
+ lost = delta/(USEC_PER_SEC/HZ);
+ offset_delay = delta%(USEC_PER_SEC/HZ);
+
+ /* update the monotonic base value */
+ monotonic_base += delta;
+ write_sequnlock(&monotonic_lock);
+
+
+ /* compensate for lost ticks */
+ if (lost >= 2)
+ jiffies += lost - 1;
+
+ /* don't calculate delay for first run,
+ or if we've got less then a tick */
+ if (first_run || (lost < 1)) {
+ first_run = 0;
+ offset_delay = 0;
+ }
+
return;
}
static unsigned long long monotonic_clock_pmtmr(void)
{
- return 0;
-}
+ u32 last_offset, this_offset;
+ unsigned long long base, ret;
+ unsigned seq;
+
+
+ /* atomically read monotonic base & last_offset */
+ do {
+ seq = read_seqbegin(&monotonic_lock);
+ last_offset = offset_tick;
+ base = monotonic_base;
+ } while (read_seqretry(&monotonic_lock, seq));
+
+
+ /* Read the cyclone counter */
+
+ this_offset = inl(pmtmr_ioport) & ACPI_PM_MASK;
+ /* convert to nanoseconds */
+ ret = base + ((this_offset - last_offset) & ACPI_PM_MASK);
+ ret = cyc2us(ret)*1000;
+ return ret;
+}
+
/*
* copied from delay_pit
*/
@@ -106,21 +176,10 @@ static unsigned long get_offset_pmtmr(vo
offset = offset_tick;
now = inl(pmtmr_ioport);
- now &= 0xFFFFFF;
- if (likely(offset < now))
- delta = now - offset;
- else if (offset > now)
- delta = (0xFFFFFF - offset) + now;
+ now &= ACPI_PM_MASK;
+ delta = (now - offset)&ACPI_PM_MASK;
- /* The Power Management Timer ticks at 3.579545 ticks per microsecond.
- * 1 / PM_TIMER_FREQUENCY == 0.27936511 =~ 286/1024 [error: 0.024%]
- *
- * Even with HZ = 100, delta is at maximum 35796 ticks, so it can
- * easily be multiplied with 286 (=0x11E) without having to fear
- * u32 overflows.
- */
- delta *= 286;
- return (unsigned long) (delta >> 10);
+ return (unsigned long) offset_delay + cyc2us(delta);
}
diff -puN Documentation/kernel-parameters.txt~acpi-pm-timer-fixes Documentation/kernel-parameters.txt
--- 25/Documentation/kernel-parameters.txt~acpi-pm-timer-fixes Mon Nov 17 12:09:48 2003
+++ 25-akpm/Documentation/kernel-parameters.txt Mon Nov 17 12:09:48 2003
@@ -214,7 +214,7 @@ running once the system is up.
Forces specified timesource (if avaliable) to be used
when calculating gettimeofday(). If specicified timesource
is not avalible, it defaults to PIT.
- Format: { pit | tsc | cyclone | ... }
+ Format: { pit | tsc | cyclone | pmtmr }
hpet= [IA-32,HPET] option to disable HPET and use PIT.
Format: disable
diff -puN drivers/acpi/Kconfig~acpi-pm-timer-fixes drivers/acpi/Kconfig
--- 25/drivers/acpi/Kconfig~acpi-pm-timer-fixes Mon Nov 17 12:09:48 2003
+++ 25-akpm/drivers/acpi/Kconfig Mon Nov 17 12:09:48 2003
@@ -263,5 +263,24 @@ config ACPI_RELAXED_AML
particular, many Toshiba laptops require this for correct operation
of the AC module.
+config X86_PM_TIMER
+ bool "Power Management Timer Support"
+ depends on X86 && ACPI
+ depends on ACPI_BOOT && EXPERIMENTAL
+ default n
+ help
+ The Power Management Timer is available on all ACPI-capable,
+ in most cases even if ACPI is unusable or blacklisted.
+
+ This timing source is not affected by powermanagement features
+ like aggressive processor idling, throttling, frequency and/or
+ voltage scaling, unlike the commonly used Time Stamp Counter
+ (TSC) timing source.
+
+ So, if you see messages like 'Losing too many ticks!' in the
+ kernel logs, and/or you are using a this on a notebook which
+ does not yet have an HPET (see above), you should say "Y"
+ here.
+
endmenu
_